Switching to bioplastic may exacerbate ingestion of lost and discarded fishing gear by marine invertebrates

Abstract

Bioplastics are argued to be more environmentally sustainable than conventional plastics. Yet, little is known about how bioplastics degrade in marine environments or their likelihood of being ingested by animals. We measured changes in the weight of biodegradable, semi-biodegradable, and non-biodegradable fishing gears (soft plastic lures, SPLs) in or out of seawater over 14 days. We then exposed new and preconditioned SPLs to soldier crabs Mictyris longicarpus and green paddle worms Phyllodoce novaehollandiae. Biodegradable SPLs gained or lost up to 70% of their weight, likely due to changes in water content, but there was little change in nonbiodegradable and semi-biodegradable SPLs. Both animals ingested biodegradable SPLs, but not non-biodegradable SPLs. Crabs also ingested semi-biodegradable SPLs. Biodegradable SPLs shed up to 8 times more glitter microplastics when crabs were present than absent. Switching from conventional plastics to bioplastics may make lost/discarded fishing gear more likely to be ingested by marine invertebrates.